Stromatolites of Shark Bay

Shark Bay has the world’s most diverse and abundant examples of living marine stromatolites. These ‘living fossils’ have helped scientists unravel the history of life on Earth. The stromatolites were a major factor in Shark Bay being declared a World Heritage Area.

Living fossils

Stromatolites are rock-like structures built by microbes (single-celled cyanobacteria, also known as blue-green algae). Shark Bay’s stromatolites are only 2,000 to 3,000 years old, but they are similar to life forms found on Earth up to 3.5 billion years ago! They provide a unique insight into what the world was like at the dawn of time.

Until about 500 million years ago, stromatolites were the only macroscopic evidence of life on the planet.

The microbes that built the stromatolites were an essential building block for the evolution of more complex life forms.

One kind of microbe found in Shark Bay is thought to have descended from an organism that lived 1.9 billion years ago – one of the longest continuing biological lineages known. Learn more about Shark Bay’s living fossils here.

What do stromatolites look like underwater?

Where to see the stromatolites

Hamelin Pool is one of only three places on Earth where you can see living marine stromatolites. (The other two places are in the Bahamas.) Stromatolites are found in Hamelin Pool because its water is twice as salty as normal seawater. Few predators and competitors can survive these conditions, allowing the microbes to flourish and form stromatolites much as they did billions of years ago. Learn how the marine geology is so important in the life of stromatolites here.